FORMATION OF SILICON NANOCLUSTERS DURING THE REACTION OF BETA-IONONE WITH TETRACHLOROSILANE

The chemical reaction between beta-ionone and tetrachlorosilane yields silicon nanoclusters entrapped in a polysiloxane matrix along with a cyclized product of beta-ionone as a side product. The IR spectrum obs erved in the entire region of 1000-1200 cm(-1) indicates the polymer c hain length, while UV absorption at 320 mm shows the presence of exten ded pi-conjugation in the system. Photoluminescence spectrum shows a b road band with a maximum at 724 nm and is qualitatively similar to tha t of porous silicon and related q-particles. Transmission electron mic roscopy and selected area electron diffraction analysis show the prese nce of embedded nanocrystalline Si particles of average particle size 50-60 nm. ESR spectrum shows a sharp signal with a g value of 2.0138 d ue to the dangling bonds of silicon clusters, while cyclic voltammetry gives a reversible peak with E-1/2 at +1.92 V and an irreversible pea k at -0.48 V vs saturated calomel electrode (SCE) confirming the mecha nism of reductive silylation of the conjugated ketones.